Paper-making machine and method



Se t. 12, 1933. R. H. KRUSE 1,925,292

PAPER MAKING MACHINE AND METHODv Filed May 51, 1950 Zaz we 72 for Patented Sept. 12, 1933 UNITED STATES PATENT OFFICE PAPER-MAKING MACHINE AND METHOD York Application May 31, 1930. Serial No. 458,843

20 Claims.

The present invention relates to paper-making and similar arts.

In the manufacture of paper, the web, as it is formed, is fed over heated dryer rolls to dry it.

The paper should, theoretically, leave the output end of the machine perfectly formed and dried, having a predetermined, fixed, moisture content, but this theory does not always work out, in prac tice. Many suggestions have been put forward for mechanically controlling the humidity of the paper as it leaves the machine, without actually improving, however, on the still-used, present-day, rough, hand control.

An object of the invention is to improve upon methods of and machines for making paper and the like, to the end that a more perfect product may result. Other objects will be explained hereinafter and will be particularly pointed out in the appended claims.

With these ends in view, a feature of the invention resides in so controlling the speed of the dryer rolls from the moisture content of the paper as to produce a predetermined, moisture content in the paper at the output end of the machine. The dryer rolls are properly heated to a constant temperature.

The invention will be explained more fully in connection with the accompanying drawing, the single figure of which is a diagrammatic view of apparatus and circuits constructed and arranged according to a preferred embodiment of the invention.

The drawing illustrates diagrammatically a paper-making machine, the moisture-laden pulp being fed in at 55 and the manufactured paper being led out of the machine at the output end 57 over heated dryer rolls 59. As the material is fed over the successive dryer rolls 59, it becomes more and more thoroughly dried.

The rolls are heated by steam from a steam pipe or pipes 61. The amount of steam admitted to the dryer rolls may be controlled by a handcontrolled valve 63, a pressure regulator 65, or in any other desired manner, such as a steam-meter 5 fiow control (not shown). It is preferred,--

though it is by no means essential,to maintain the temperature of the dryer rolls constant, which may be effected thermostatically, or by means of electric heaters and rheostats (not shown) though this result may ordinarily be attained merely by suitably adjusting the hand valve 63 and thereafter leaving the adjustment undisturbed. By the time that the paper leaves the machine, it. may or may not be thoroughly dried, depending upon the speed of the dryer rolls.

In accordance with a feature of the present invention, the rolls are driven at such a speed as to assure that the paper, as it leaves the output end of the machine, shall have a constant, predetermined humidity. When the moisture content of 0 the paper falls below the predetermined value, the rolls are speeded up so as to subject the paper to the action of the dryer rolls for a smaller period of time; and when the moisture content rises, the dryer rolls are correspondingly slowed down.

According to the preferred embodiment of the invention that is herein illustrated and described, the speed of the rolls is controlled by a motor 67, the rolls 59 and the pulp-feeding device 55 being preferably all controlled to speed up and slow down as a unit. Any other desired control, such as an engine governor, if an engine is used, may be substituted for the motor control, as will be understood, and the dryer rolls 59 and the pulpfeeding device 55 may be driven as a unit in any desired way, diagrammatically illustrated by belts 68. The speed of the motor 67 is controlled by a moisture-responsive device that is subjected to the action of the moisture in the paper at the output end 5'7 of the machine. Any desired moistureresponsive or moisture-absorbent controller may be employed, such as a wet-and-dry-bulb thermometer, but it is preferred to use the device diagrammatically illustrated in the drawing.

A moisture-sensitive strip 4, which may be constituted of fibres or hairs, gold-beaters skin, or any other suitably hydroscopic material, is mounted in rigid end pieces 5 and 6 and disposed in close proximity to the paper, at the output end 57 of the machine. The whole is enclosed in a housing 26 (shown in dotted lines) that should preferably be ventilated or surrounded by air the humidity of which is in equilibrium with the paper surface at the output end 57 ofthe machine. The end piece 6 is yieldingly fixed to an adjustable spring support 3. The end piece 5 is mechanically connected at 7 to a close-wound helix 8 of bare, electrical micrometer resistor wire. The resistor coil 8 forms one arm of a Wheatstone bridge, the other arms of which, respectively, contain a coil' 9, similar to the coil 8, and two ratio coils 10 and 11, which may be fixed resistors. A galvanometer 16 is connected with opposite verteces l2 and 13 of the bridge for measuring the voltage between those verteces. The bridge current is furnished by a battery 1'7 connected, in circuit with a controlling rheostat l5 and an ammeter 14, with the other two opposite verteces of the bridge. The current is coils 8 and 9 may be constituted of resistance wire, like platinum or nickel, having a relatively high temperature coefficient of resistance.

The coil 8 constitutes, in effect, a helical spring designed so as to contract and expand in respond to very light forces. Such forces are produced by the changes in length of the strip 4. The length changes in the strip 4 are accompanied by changes in the position of the end piece 5, and such changes in position control the length of the coil 8. The circuits and apparatus are so designed that the current flowing in the Wheatstone bridge shall produce a sensible temperature increase in the coils 8 and 9. When the coil 8 is expanded, therefore, its effective heatradiating space becomes increased, with the result that its temperature decreases, notwithstanding that the current from the battery 1'? is maintained constant. When the coil 8 is contracted, similarly, its temperature becomes higher. These changes in the length of the coil 8, being accompanied by changes in its temperature, involve, in turn, changes in its electrical resistance approximately proportional to its change in length, whether an expansion or a contraction. The current, as registered in the galvanometer, changes to correspond, with the result that the voltage difference between the verteces 12 and 13 becomes altered approximately in proportion to the change in length of the coil 8. The variations of the element 4 in response to moisture or humidity changes may thus be measured or recorded in the galvanometer 16. The galvanometer 16 may, of course, be situated at any convenient spot, whether close to or far away from the humidity-sensitive device 4.

By the time that the paper reaches the output end 57 of the machine, most of the moisture has been driven out of it by the heated dryer rolls 59. But that is not sufiicient. The paper, when leaving the machine, should have just the right amount of moisture content, and neither more nor less. This result is brought about by the present invention.

When the humidity of the paper at the output end of the machine rises, therefore, the galvanometer needle '70 will be actuated in one direction to contact with a contact member 69; and when the humidity falls, the needle will be actuated in the opposite direction to contact with another contact member '71. In the former case, a circuit will be established leading from a line conductor '73, through the needle '70 and the contact member 69, through a field-magnet winding 75 of a rheostat-controlling motor 7'? and, by way of a conductor '79, back to the other line conductor 81. In the latter case, the circuit will proceed as before described, but through the contact member '71 and another field-magnet winding 83 of the motor '77, instead of through the contact member 69 and the field-magnet winding '75. In the former case, the motor 77 will insert more resistance 85 into the circuit of the motor 67, and in the latter case, it will cut more resistance 85 out of the motor circuit. The speed of the motor 67 will thus be controlled in accordance with the degree of moisture content of the paper at the output end 5'7 of the machine to maintain the moisture content or humidity ofthe manufactured paper substantially constant.

Modifications will occur to persons skilled in the art, and all such are considered to fall within led to the coil 8 by way of a conductor 51. The.

the spirit and scope of the invention. as defined in the appended claims.

What is claimed is:

1. A method of feeding and drying moistureladen material by means of heated rolls that comprises maintaining the heat of the rolls substantially constant, and varying the speed of the rolls in accordance with the moisture content of the material.

2. A machine of the class described having, in combination, means for feeding moisture-laden material, means for drying the material while feeding it, moisture-absorbent means disposed in close proximity to the material, and means controlled by the moisture-responsive means for controlling the speed of feed of the material.

3. A machine of the class described having, in combination, meansfor feeding moisture-laden material, means for controlling the speed of the feeding means, and moisture-absorbent means responsive to the amount of moisture in the material for controlling the speed-controlling means.

4. A machine of the class described having, in combination, means for feeding moisture-laden material, means for heating the feeding means to cause the feeding means to dry the material, and moisture-absorbent means responsive to the amount of moisture in the material for controlling the feeding means.

5. A machine of the class described having, in combination, a plurality of rolls for feeding moisture-laden material, a source of steam supply, means for admitting a supply of steam from the source to the rolls to heat the rolls, means for maintaining the supply of steam to the rolls constant, and means for controlling the speed of the rolls in accordance with the moisture content of the material.

6. A machine of the class described having, in combination, a plurality of rolls for feeding moisture-laden material, a source of steam supply, means for admitting a constant supply of steam from the source to the rolls to heat the rolls, and moisture-absorbent means responsive to the amount of moisture in the material for controlling the speed of the rolls.

7. A paper-making machine having, in combination, means for feeding pulp to produce paper and feeding the paper so produced, a source of steam supply, means for admitting'a constant supply of steam from the source to the feeding means to heat the feeding means and thereby dry the paper, and moisture-absorbent means disposed at the output end of the machine and responsive to the moisture content in the paper at the output end of the machine for controlling the speed of the feeding means to produce a substantially constant humidity in the paper at the output end of the machine.

8. A method of feeding and drying moistureladen material by means of heated rolls that comprises maintaining the heat of the rolls substantially constant, and varying the speed of the rolls in accordance with the moisture content of the portion of the material in contact with the rolls.

9. A paper-making machine, having in combination, means for feeding pulp to produce paper, a plurality of dryer rolls for feeding the paper and drying it, means for maintaining the heat of the rolls substantially constant, and means for controlling the speed of the pulp-feeding means and the rolls in accordance with the moisture content of the material.

10. A paper-making machine having, in combinaton, means for feeding pulp to produce paper and feedingthe paper so produced, and moistureresponsive means disposed at the output end of the machine and responsive to the moisture content in the paper at the output end of the machine for controlling the speed of the feeding means to produce a substantially constant humidity in the paper at the output end of the machine.

11. A method of drying moisture-laden mate rial while feeding it that comprises controlling the speed of feed of the material in accordance with the moisture content of the material when the moisture content of the material is such that air in close proximity thereto is less than 100% saturated.

12. A method of drying moisture-laden material while feeding it that comprises controlling the speed of feed of the material in accordance with the moisture content of the material when the moisture content of the material is such that air in close proximity thereto is less than 100% saturated to maintain the moisture content of the material constant.

13. A machine of the class described having, in combination, means for feeding moisture-laden material, means for drying the material while feeding it, and means for controlling the speed of feed of the material in accordance with the moisture content of the material when the moisture content of the material is such that air in close proximity thereto is less than 100% saturated.

14. A method of feeding and drying moistureladen material by means of heated rolls that comprises increasing the speed of the rolls when the moisture content of the material decreases and decreasing the speed of the rolls when the moisture content of the material increases.

15. A method of feeding and drying moistureladen material by means of heated rolls that comprises maintaining the heat of the rolls substantially constant, and increasing the speed of the rolls when the moisture content of the,material decreases and decreasing the speed of the rolls when the moisture content of the material increases.

16. A machine of the classdescribed having, in combination, means for feeding moisture-laden material, means for drying the materialwhile feeding it, and moisture-absorbent means for in creasing the speed of feed of the material when the moisture content of the material decreases and for decreasing the speed of feed of the material when the moisture content of the material increases.

17. A machine of the class described having, in combination, means for feeding moisture-laden material, and moisture-absorbent means responsive to the amount of moisture in the material for increasing .the speed of feed of the material when the moisture content of the material decreases and for decreasing the speed of feed of the material when the moisture content of the material increases.

18. A machine of the class described having, in combination, means for feeding moisture-laden material, means for heating the feeding means to cause the feeding means to dry the material,

' and moisture-absorbent 'means responsive to. the

in combination, a plurality of rolls for feeding moisture-laden material, a source of steam supply, means for admitting a constant supply of steam from the source to the rolls to heat the rolls, and means for increasing the speed of the rolls when the moisture content of the material decreases and for decreasing the speed of the rolls when the moisture content of the material increases.

20. A paper-making machine having, in combination, means for feeding pulp to produce paper, a plurality of dryer rolls for feeding the paper and drying it, means for maintaining the heat of the rolls substantially constant, and means disposed between adjacent rolls for controlling the speed of the rolls in accordance with the moisture content of the material.

RALPH H. KRUSE. 

